A motor vehicle generally has a windshield wiper controlled to remove water and dust from the windshield glass thereof during the rain so that the driver can see through the windshield clearly while driving. Since the rear view mirrors of a motor vehicle may also be contaminated by dust or blocked up by rain water, they must be protected against rain water and washed regularly so as to clearly reflect the images of objects. The present invention has been accomplished under the aforesaid circumstances.